Oxidative DNA damage in the mucosa of ulcerative colitis increases with disease duration and dysplasia.

Abstract

Chronic inflammation may contribute to cancer risk through the accumulation of specific products as a result of DNA damage. The role of free radical mediated oxidative DNA damage during inflammation was determined in patients with ulcerative colitis by measuring 8-hydroxydeoxyguanosine (8-OHdG). Patients with ulcerative colitis were compared according to age, gender, duration and extent of disease, endoscopic and histologic activity, presence or absence of dysplasia/cancer, and biochemical parameters of inflammation. Patients with sporadic colon cancer and irritable bowel syndrome served as controls. Levels of 8-OHdG were assessed by high pressure liquid chromatography with electrochemical detection (mean number of adducts/10(5) dG residues). Patients with ulcerative colitis and dysplasia had significantly higher mucosal 8-OHdG concentrations (P = 0.011). 8-OHdG concentrations were significantly higher in older patients (P = 0.010), patients with long-standing disease (P = 0.015), active endoscopic (P = 0.006) or histologic disease (P = 0.003). Covariance analysis showed significant effect of dysplasia on 8-OHdG levels: values higher than 100 adducts/10(5) dG had a diagnostic value of 80.9% (SE 6.2%). Oxidative DNA damage accumulates with the duration of the disease in ulcerative colitis reaching maximal increase if dysplastic lesions are found with possible implications for mutagenic and carcinogenic progression.